Enols and enolate ions are essential intermediates in many biological reactions this application describes a program of research designed to investigate the chemistry of biologically important enols for the purpose of providing basic information needed to understand the functions and modes of action of these substances. The investigation would be conducted using techniques which the Principal Investigator has recently developed for studying simple unstable enols in aqueous solution. These include flash photolytic generation of enols by Norrish type II photoelimination, photooxidation-reduction, and photolytic removal of protecting groups, as well as thermal production of enols by hydrolysis of metal enolates and silyl enol ethers. Rates of ketonization of the enols would be measured as well as rates of enolization of their keto isomers; these data would provide keto-enol equilibrium constants and also acidity constants of the enols ionizing as oxygen acids and their keto isomers ionizing as carbon acids. Work would be continued on the enols of thiol esters and mandelic and pyruvic acids, for the purpose of understanding the modes of action of coenzyme A and mandelate racemase as well as the mechanism of the "uncatalyzed" ketonization of pyruvate enol. New research would also be initiated on enediols and the enol of proline, the former to provide information relevant to the enzymatic isomerization of saccharides, especially that catalyzed by triosephosphate isomerase, and the latter in order to furnish a non-enzymatic reaction base against which to assess the efficiency of the process promoted by proline racemase.